In many applications and environments, costly items such as medical equipment, and restricted items such as certain medical supplies, are contained in cabinet drawers and in compartments located behind the doors of medical cabinetry that is normally kept locked. Persons such as doctors and nurses who are authorized to access these items often find themselves opening and closing the locked doors and drawers of medical cabinets frequently during nearly every busy workday.
Many other applications need locks or latches that automatically relock or relatch in response to the closures that carry the locks and latches being returned to closed positions after being deliberately opened—including, for example, the doors and drawers of cabinetry installed on sea-going vessels that need to be held releasably closed even when these craft are subjected to rocking action caused by waves during inclement weather.
A type of relatively inexpensive keyed or nonkeyed lock that has gained wide acceptance during decades of use on cabinets and the like, has a tubular housing that is mountable in an opening formed through each cabinet closure that needs to be releasably retained. The type of keyed or non-keyed lock being referred to here has an operating mechanism that extends forwardly-rearwardly through the tubular housing. At or near the front of the tubular housing, components of the operating mechanism define a forwardly-opening keyway into which an operating key can be inserted. At or near the rear of the tubular housing, the operating mechanism defines a rearwardly extending formation that drivingly engages a transversely extending cam. When a correctly-configured operating key is inserted into the keyway at the front of the lock, and is turned, the elongate cam that is connected to the formation of the operating mechanism at the rear of the lock is turned a corresponding amount such that the turning of the inserted operating key causes the operating mechanism to turn about a forwardly-rearwardly extending axis of the tubular housing of the lock. Keyed versions of such products are commonly called “cam locks.” Non-keyed versions of such products (that may have thumb-turned operating mechanisms) are sometimes called “cam latches,” or are included (as they are in this document) in what are called “cam locks.”
When the elongate cam of a conventional cam lock on a cabinet closure (such as a cabinet door or a cabinet drawer front) is in, or is turned to, its locked orientation WHILE THE CLOSURE IS CLOSED, a distal end region of the elongate cam extends behind or reaches behind a nearby stationary component of the associated relatively stationary cabinet structure to thereby prevent forward movement of the closure away from where the closure is being retained in its locked position—which is because the elongate cam cannot move forwardly when it is extending behind or reaching behind the associated cabinet component of what is typically a stationary cabinet.
When the elongate cam of a conventional cam lock on a cabinet closure (such as a cabinet door or a cabinet drawer front) is in, or is turned to, its unlocked orientation WHILE THE CLOSURE IS CLOSED, the distal end region of the elongate cam does not extend behind or reach behind any nearby stationary component of the associated stationary cabinet—which means the associated cabinet closure is unlocked and can be moved between the closed position and the open position (and back again) because the cam does not limit the opening and closing movement of the closure.
When the elongate cam of a conventional cam lock mounted on a cabinet closure (such as a cabinet door or a cabinet drawer front) is in, or is turned to, its locked orientation WHILE THE CLOSURE IS OPEN, the distal end region of the elongate cam does not extend behind or reach behind any nearby stationary component of the associated stationary cabinet—which means that, although it may be possible to push the closure at least some of the distance toward its fully closed position, IT IS NOT POSSIBLE TO PUSH THE CLOSURE ALL OF THE DISTANCE TOWARD ITS FULLY CLOSED POSITION because, although the distal end region of the elongate cam does not extend or reach behind any nearby stationary component of the stationary cabinet, the distal end region of the elongate cam nonetheless does extend away from where it is carried LIKE A RED FLAG FORECASTING BAD WEATHER—and, if the closure is pushed vigorously toward its fully closed position, the distal end region of the elongate cam will come quickly into contact with a front face of the same stationary cabinet component that the distal end region reached behind or extended behind when the closure was being locked in its closed position.
A sudden and abrupt halt that can unexpectedly occur while the closure is being vigorously (and perhaps forcefully) pushed to or toward the closure's closed position is sometimes accompanied by a rather loud and startling “WHAM” or even an embarrassing and attentiondrawing “THUD” as the distal end region of the elongate cam impacts the same stationary cabinet component that the elongate cam reached behind when the closure was locked in its fully closed position (or when the distal end region of the elongate cam strikes some other stationary cabinet component located in front of said stationary component).
What is described just above is sometimes called the “IMPACT PROBLEM ASSOCIATED WITH CONVENTIONAL CAM LOCKS.” It is depicted in FIG. 3, and will be discussed shortly.
If and when the distal end region of the elongate cam strikes a stationary front surface of the cabinet closure, this can damage the front surface of the cabinet component that is impacted by the distal end region of the elongate cam. If the so-called IMPACT PROBLEM occurs repeatedly or often, the damage caused to the front surface of the stationary cabinet component that is struck by the extended distal end region of the elongate cam can become extensive and unsightly.
If the IMPACT PROBLEM has occurred as the result of a disgusted user of the cabinet being aggravated by the failure of the closure to properly close, damage caused by the IMPACT PROBLEM may escalate—perhaps resulting in the closure being again slammed, perhaps even more forcefully in an effort to shut the obstinate closure—and, this time, the resulting damage may be even more extensive—perhaps even causing damage to the extended elongate cam itself, or even causing the elongate cam to become detached, dislodged or disconnected from a rearwardly extending formation of the lock operating mechanism (that needs to have a secure connection to the elongate cam to pivot the elongate cam between its locked and unlocked orientations.
It frankly does not matter WHY the elongate cam carried by a closure-mounted a cam lock has gotten itself turned to its locked orientation while the associated closure has been in its open position. (Actually, there are some good reasons why the cam of a cam lock carried by a closure may have gotten itself pivoted to a locked orientation while the closure is in its open or opened position—an example being that some cam locks only permit key removal when the lock has been turned to its locked orientation—and, because people sometimes do not want to leave keys where they might be pulled from the keyways of locks, they turn the cam locks to their locked orientations, so they can remove a key and take it with them while the closure remains in an opened position.)
Some efforts have been made by others during relatively recent years to upgrade the operating mechanisms of conventional cam locks (and cam-like locks) that are (or are intended to be) mounted on closures, to give such closures “slam capability.” Some of these efforts have sought to replace the elongate cams traditionally carried by cam locks with assemblies of components that permit closures (that carry the enhanced cam lock operating mechanisms) to move to their fully closed positions without any need to first pivot the cam of an enhanced c am lock operating mechanism to its unlocked orientation.
Southco, Inc. did some work along these lines that dates back at least as far as the Fall of the year 2004, as is shown by Southco's applications 2004/0183312 published on Sep. 23, 2004, and 2005/0151378 published on Apr. 4, 2006, that eventually became Southco's U.S. Pat. No. 6,854,774 issued Feb. 15, 2005, and U.S. Pat. No. 7,021,679 issued Apr. 4, 2006, respectively.
A mechanically similar retractable latch bolt assembly appears to be disclosed in a Design Patent that is assigned on its face to Fort Lock Corporation, namely Patent D-365,011 issued Dec. 12, 1995; and, is more clearly disclosed in a published application of CompX International Inc. 2014/0319849 dated Oct. 30, 2014.
Although the mechanism proposals contained in the several the documents referenced above can be used to provide closures with a slam capability, each of these proposals calls for the use of a relatively large housing to be mounted at the rear of the operating mechanism of a cam lock (or a cam-like lock), with the relatively large housing surrounding a relatively small retractable latch bolt component that is biased outwardly with respect to its associated housing through an opening defined by the housing. The small latch bolts are not closely confined by pairs of surfaces defined by components that reach into hollow regions of the small latch bolts to confine latch bolt movement to specific travel paths. Each of the bulky housings contain little more than a compression coil spring that biases the small associated latch bolt outwardly with respect to the interior of the housing.
The slam-capability proposals contained in the published applications and patents identified above are mechanically similar in that the assemblies suggested by these proposals do include any components that extend into hollow interiors of, or through openings defined by sidewalls of the relatively small latch bolts that are biased outwardly through the relatively small openings defined by the relatively large housings that are called for by the proposals found in the documents identified above.